The present invention concerns an automatic control system for a supplemental brake system known as a retarder incorporated in dump trucks or like motor vehicles.
Dump trucks for ore transportation from mines usually take resort to the retarder for controlling the vehicle speed while going downhill. The vehicle operator has heretofore relied on his own discretion in manipulating the retarder. The degree to which the retarder actually retards the vehicle, however, varies greatly depending upon the gradient of the slope and the load on the vehicle. It has therefore been difficult for the operator to effect optimum control of the vehicle speed in accordance with the specific conditions of the road and the vehicle. Thus, while the vehicle is traveling down a long or steep slope, the retarder has been easy to overheat, eventually resulting in the rupture of the brake discs in the worst case.